Skid indicator



Jan. 16, 1951 R. E. JENNINGS 2,538,003

SKID INDCTOR Filed Nov. 2l, 1946 2 SheerLs-Sheet l ATTORNEY R. E.JENNINGS SKID INDICATOR Jan, 16, 1951 2 Sheets-Sheet 2 Filed NOV. 2l,1946 lNvENToR R14/,PH E. JENN//VG5 ATTORNEW Patented Jan. 16, 1951 sinnnmIcAToR ,Ralph Edward Jennings, UnitedStates Navy, Was`1iington, 1). C.

Application -NmmhcnZI, 194B, 'Seria1No. 711,335

-(Grantcd `under the act of 'March 13, 1883, as `amended .April 13,0,1928; 370 I). G. 757') 9 Claims.

This invention relatesgenerallyto -instruments adapted-tofurnish'aperceptibleindication of any transverse motion in a` fluid'medium of -a moving body; particularly, lthe invention Irelates `to`slrid indicators for aircraft.

It is well known that bombing accuracy is decreased when the aircraft isin a skid at the moment `of release, the reason being that, -underskidding conditions, t-he 1flight `path Aof `the Haircraft (along which-theibomb will drop) is not the `sameasfthe line-oi sight 4from `planetoitarget. This error 'is not introducedwwhen `the aircraft `is inaproperly coordinatedpor Ibanked, `turn at the momentof release-since theline of `sight in such turns `will Lbe tangent to the "lineof -flig'htof the aircraft.

An instrument :capable of informing the `pilot or bombardier of VevenAthe slightest skidding `of his :aircraft is, thereore, of `great valueboth 1in `training and in actual bombingoperations, :and

it is tosuch an instrument -thatthe presentinvention Ais directed.

Accordingly, an object of the invention is to provide a devicewhichwilllindicateevena'slight diversion of *the aircraft :from its Lheading"in an air mass.

Another object of the inventori is the provision of such `a `devicewhich will depend for;its operation upon :an` :air npressure`differential produced between `.the 'branches of sa conventionalfyawhead or Vother pressure responsive device `under :skiddingconditions.

An additional l.object `is to provide `a flight.- .weightskidrindicatorfwhichwmay b eieasiiy andinexpensively .constructed iandinstalled in an aircraft and which `will frequire la minimum 10i 4rcarein maintenance.

. Other 'and `further fobjects land :advantages of theiinvention, and:thefmanner-in which `theyanay he attained, will become :apparent from`the .following `detailed .description Vwhen ,read in iconnection 1withthe drawingszaforming `a partei this specification.

' In'ltherdrawings:

Fig. 1 is "alongitudinal `fsectional "rew fof the particularly in Fig.1,a selectorvalve Li I -is operal chamber *i6 0of relatively large`cross-sectional areanandendsockets -ilfl and 2111". Aplunger gi: havinga, 'centra-l Lseat portion -or partition finemberiQrintermediatelproections 25j thereof `imposttioned within thelcasing H`in -slidable engagei merit with -the walls of chamber i6 c and `the:suckiets. lCoiled Springs2xl disposedtbetweenitheprojections 127D.ofithe plungertvand shoulders 1 2 :all the extremities `ofsocketsitil., `I 51" serve to maintain the .plunger i8 centralized zwitghinchamber i6 as l shown. .:Gonnectorrtubes ZSlandZ- arelattachadskid-indicator `of :the :rinventi-on, `showing :its vrela to the rendsof rca-sine :L4 ,opnositesockets Al l, lI J brani convenientfmeans,asconventonalgeas ntf tinge `2.6., thus establishing`rcorrrirrurlication between :the-sockets A.andthe Pitotlqpenings 21`and 28 of -yawhead 1,2, Chamber Ifland sockets Il, `Il" :are`preferably n,circular in V,cross-section; the sockets, additicnally,are equal.inicross-sectional area so as `to ,assurezproper centering ofplunger i8 -when the l pressures insockets :1.1 .and .l .1 are l ofequal magnitude.

A Yawhead :l2 Ais designed `to he attached Lto `the leadingedge cfa wing.di an ,airplanein ahori-` zontal .plane Aand with Lits longitudinalaxis par-` allel `.to,thelongitud inal.axisoi the airplane The Pitot.openings 2'! and '28`are 'inclined at equal angles on ,opposite sides`o'f the longitudinal -axis o'f the yawhead so thatariy .movement oftheyawhead tendingto align-one of the YPitot openings with'the relativeWind, which is -an incident Jci skidding, results in -a Adifferentialpressure between the twp Pitot openings. These "pressures, ofcourse,`are transmitted through 4tubes 23 and Ziiito sockets -I -an'clflfl atopposite-endsfofplung? er "i8 and, where a pressure differential exists,plunger :f8 Awill be translated inthe `direction-of the lower pressurejPitot scoep 4i3 `is `attached externally of the aircraft and with itsscoop opening forward -in the "slip dstream, 'thus fmainta'imng -air at-h-igh scoop with the selector valve Il. *The 4:inletril from the Pitotscoop lis normally :closed by the seatlportion 2119 of ithe plunger andmay lfintroduce air `:under ipressure :into lchamber llt only `.when theplunger iis displaced 1in either direction `due to :a .pressurerdiilerential in the .sockets flz'l, itil. Rorts 3| andf32lcommunicate@with chamber @LB on:either-side of the .igseat :portion `i9 and :are

`adapted :to Aconduct zar-way .any gases :int-reduced into chamber I6.through theinlet r3.1! :when .the

3 plunger I8 is moved in either direction away from inlet 38.

Thus, it is seen that the selector valve II may function as a servomechanism, delivering relatively large quantities of air through ports3| and 32 where only relatively small differences in pressure existbetween sockets II and Il', and it is obvious, furthermore, that theyawhead may be so connected with the selector valve that the directionin which the aircraft is skidding may be indicated by delivery of airfrom the Pitot scoop to either of the ports 3I or 32.

Since delivery of a pulse of air through either of the ports 3i or 32has a directional significance with reference to skid, such air pulsesmay be utilized to notify the pilot of the direction of a skid when itexists. I prefer to employ these air pulses directly by conducting themby any convenient means, as by air lines or conduits 34 and 35, to aremote point of application such as the interior of the pilots helmetwhich is the common terminal of said conduits, so that a skid in anydirection will result in a corresponding gentle blast of air on thecorresponding cheek.

Referring now to Fig. 2, the yawhead I2 is mounted in the leading edgeof the port wing of an aircraft and the Pitot openings thereof areconnected by means of tubes 23 and 24 to the opposite ends of theselector valve I I. Pitot scoop I3 may be attached to any convenientexterior surface of the aircraft; in Fig. 2 the Pitot scoop is shownsecured to the exterior wall of the cabin.

In. the modification shown in Fig. 3, the yawhead i-s replaced by a vane36 positioned in a passage 3l in the aircraft wing and pivoted at itsforward end, as at 33; thus the vane at all times aligns itself with therelative wind. A pulley 39 which is xed to the vane, cooperates withpulleys 4i), 4I and 42, and cable 43 to transmit any rotary motion ofthe vane to the plunger I8 of the selector valve II. When the aircraftskids, the vane 3l is rotated, displacing the plunger I8 through thesystem of cables and pulleys; the skid is then indicated to the pilot asabove described.

Operation of the skid indicator illustrated in Figs. 1 and 2 isextremely simple and reliable. Consider an installation in which theyawhead I2 is mounted in the left wing and the Pitot scoop I3 isattached to the right side of the fuselage, substantially as shown inFig. 2. A skid to the left will result in a higher pressure in Pitotopening 28 than that in Pitot opening 21; these pressures aretransmitted respectively to sockets Il and I'I and, since the pressurein socket I'I will be greater than that in socket I'I' plunger I8 willbe displaced in the direction of socket I'I until the pressures in bothsockets are equal. This' displacement of plunger I8 permits air underpressure from Pitot scoop I3 to enter chamber I6 whence it is conductedthrough port 3I and flexible tube 35 to the left side of the pilotshelmet where it blows against the left side of the pilots face informinghim that he is skidding to the left.

vThe Pitot scoop employed with the skid indicator may be theconventional ventilator scoop; this scoop is adjustable to meet the airstream at any pre-determined angle and, since such adjustment willaffect the air pressure in delivery tube 23, the pilot has a controlover the sensitivity of the skid indicator. When the signal airdelivered by the Pitot scoop is cold and may dull the sensitivity of theareas irnpinged, provision for heating the air by any suitable means maybe made.

It is obvious that the signal air delivered from the selector valve maybe employed in a number of ways to convey knowledge of a skid to thepilot, and although I prefer to employ the air signals directly bycausing them to impinge upon some portion of the pilots body, thusmaking use of his sense of touch, use of such signals to Vvcreate asecondary signal perceptible to the pilot by any of his other senses iswithin the contemplation of the present invention. Therefore, while whathas been described herein is particularly illustrative of a presentlypreferred embodiment of my invention, it is not intended that the scopeof the invention be limited thereto but that it embrace anymodifications and changes which fall within the true spirit of theinvention, as covered by the appended claims, occurring to those skilledin the art.

The invention herein described may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

I claim:

'1. A skid indicator for aircraft comprising a yawhead having at leasttwo openings to the atmosphere, a valve casing having a chamber op-`erationally interposed between said openings, said openingscommunicating with opposite ends of said chamber, a partition memberdisposed within said chamber and movable in response to pressuredifferences between the ends thereof, a source of fluid pressure havingan inlet communicating with the chamber medially of its ends, meanstending to maintain said partition member in closing position over saidinlet, a pair of conduits respectively extending from said chamber atopposite sides of said partition to a remote point, means carried bysaid partition member separating said fluid pressure inlet and saidconduits from said opposite ends of the chamber, and outlet meansconstituting the common terminal of said conduits at said remote point.

2. A skid indicator for aircraft comprising a yawhead having at leasttwo openings to the at mosphere, a valve casing having a chamberoperationally interposed between said openings, said openingscommunicating with opposite ends of said chamber, a plunger in thecasing being movable in response to pressure differences between saidends and having a partition member disposed within said chamber, asource of fluid pressure having an inlet communicating with the chambermedially of its ends, means acting on the plunger to tend to maintainsaid partition member in closing position over said inlet, a pair ofconduits respectively extending from said chamber at opposite sides ofsaid partition to a remote point, means carried by said partition memberseparating said fluid pressure inlet and said conduits from saidopposite ends of the chamber, and outlet means constituting the commonterminal of said conduits at said remote point. 1

3. A skid indicator for aircraft comprising a yawhead having at leasttwo openings to the atmosphere, a valve casing having a chamberoperationally interposed between said openings, said openingscommunicating with opposite ends ofv said chamber, a partition memberdisposed 1 within said chamber and movable in response a source of airpressure, including a Pitot scoop, having an inlet communicating withthe chamber medially of its ends, means tending to maintain saidpartition member in closing position over said inlet, a pair of conduitsrespectively extending from said chamber at opposite sides of saidpartition to a remote point, means carried by said partition memberseparating said fluid pressure inlet and said conduits from saidopposite ends of the chamber, and outlet means l constituting the commonterminal of said conduits at said remote point.

4. A skid indicator for aircraft comprising a yawhead having twoopenings to the atmosphere, a valve casing having a central chamber ofenlarged diameter and end portions of reduced diameter, said casingbeing operationally interposed between said openings, said openingscommunicating with said end portions of said casing,

a piston having an intermediate portion of en larged diameter disposedwithin said casing such that the end portions of said casing areseparated from said central chamber by said piston, said piston beingmovable in response to air pressure differences between the endsthereof, a source of air pressure having an inlet communicating withsaid central chamber and normally adapted to be closed by saidintermediate portion of said piston but adapted to introduce air intosaid chamber on one side of said piston when the latter' is moved ineithel` direction, means acting on the piston to tend to maintain saidenlarged intermediate portion over said inlet a pair of conduitsrespectively extending from said chamber on opposite sides of saidenlarged portion of said piston to a remote point, and outlet meansconstituting the common terminal of said conduits at said remote point.

5. The skid indicator set forth in claim 1 in which the openingsadjacent the atmosphere are equally diverted from an axis parallel tothe longitudinal axis of the yawhead, whereby rotation of said yawheadabout a vertical axis produces a pressure differential between saidopenings.

6. A skid indicator for aircraft comprising a pivotal vane adapted toalign itself with the relative wind of the aircraft, a pulley fixed tosaid vane at its pivot point, a valve casing having a chamber, a plungermovable within said chamber, a cable cooperating with said pulley andconnected to opposite ends of said plunger whereby deflection of thevane on its pivot and consequent rotation of said pulley results in acorresponding movement of said plunger terminating at an inlet in saidcasing and, a source of air pressure normally adapted to be closed bysaid plunger, a pair of conduits respectively extending from saidchamber at opposite sides of said plunger to a remote point andrespectively receiving an influx of air from said source as the inlet isuncovered by the plunger upon said plunger movement, and outlet meansconstituting the common terminal of said conduits at said remote point.

7. A skid indicator for aircraft comprising means directed into therelative Wind of the aircraft and operative to effect a wind impulse inresponse to an air pressure differential between the sides of saidmeans, a valve casing, valve means in said casing movable in response tosaid pressure differential, a pressure line to conduct a portion of theaircraft slip stream to the valve means for distribution, and means towhich said slip stream portion is conducted through distribution by saidvalve means to produce a signal capable of affecting one of the humansenses.

` 8. A skid indicator for aircraft comprising means directed into therelative wind of the aircraft and having diversely directed openingsoperative to produce a signal in response to an air pressuredifferential between the sides thereof at which said openings occur, avalve casing having a chamber the opposite ends of which are operativelyconnected with the respective openings, a plunger disposed Within saidchamber having its ends confronting said chamber ends and movable insaid chamber in response to pressure differentials at said ends, asource of air pressure terminating at an inlet in said casing andnormally adapted to be closed by said plunger, a pair of conduitsrespectively extending fromsaidl chamber at opposite sides of saidplunger to a remote point, means partitioning said air pressure inletand said pair of conduits from said opposite ends of the chamber, andoutlet means constituting a common terminal of said conduits at saidremote point.

9. An operator-controllable vehicle progressively movable in a fluidmedium, means on the vehicle for deflecting a portion of the fiuid slipstream produced by the heading movement of the vehicle in said medium toprovide a pressure source, pressure means responsive to the diversion ofthe vehicle from its heading, and means actuated by said pressure meansfor selectively orienting and conducting said deflected fluid portion toa point of application for affecting at least one of the senses of theoperator.

RALPH EDWARD JENNINGS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,107,298 Haas Aug. 18, 19141,638,101 Roucka Aug. 9, 1927 2,029,700 Boykow Feb. 4, 1936 2,237,306Hood Apr.. 8, 1941 2,246,555 Underwood June 24, 1941 2,266,921 ThanteranDec. 23, 1941

